Diaphragm indicator for cameras



Aug. 17,1926. 4 1,596,023

W. G. RICKMAN DIAPHRAGM INDICATOR FOR CAMERAS Filed August 10. 1922 Sheets-Sheet -1 Aug. 17-, 1926. 1,596,023 W. .G. RICKMAN 1 DIAPHRAGM INDICATOR FOR CAMERAS Filed August 10. 1922 '2, Sheets-Sheet 2 Patented Aug. 17, 1926.

umrsn STATES g A 1,596,023 PATENT OFFICE.

WILLIAM enoneamcxusn, or Lennon, ENGLAND.

My DIAPHBAGI I INDICATOR FOR CAMERAS.

" Application filed Kugust' 1o,'192a', seria1 no. 581,033, and 1.. Great Britain May 9, 1922.

My invention relates-to newand useful improvements in camera attachments and more particularly to'a device for indicating the reduced light intensity-value of the apertures of lenses when used at a considerable extensionof the camera.

In the use of lenses for photographing near objects, copying, enlarging, reducing and the like, the camera has to be drawn out beyond the normal focal distance at which objects at infinite distance are in sharp focus, in'some cases to such an extent, as for instance when copying the object the same size, that the extension of the camera is double that necessary for objects at: in-

finity distance. The extension of. thecameramay in some cases be considerably'more than this, for instancewhenmaking'a negative in the camera onan enlarged scale. .The rapidity orlight intensity value of the apertures of a lens used at such'increased focal'distance is consequently reduced thereby necessitating, as is well known, a longer exposure, varying'as the square'of the focal distance. I

My invention consists of a device for indicating the diminished light intensity value of the diaphragm numbers on lenses when the camera is extended beyond the normal. focal distance at which objects at an infinite distance are-in sharpfocus, this be ing done automaticallywith the extension of the camera, without recourse to measurement or calculation.

Most lenses are now marked with the F/ numbers or the U. S. (uniform system),

numbers as follows;-

In the case of the F/ the diameter of the effective aperture of the lens is ex ressed a fraction'of the normalifocal ength of the lens, while in the case of the uniform system the aperture ofiF/ ."3 taken as the unit and the other a ertures are given numbers proportional to t erequired. exposures. Various other systems of marking the diaphragm numbers of'lenses have been in use and my invention can be used with any of said systems.

, tie the eneral practice ofa-photogra pher when p otographing objects requiring With the foregoing in mind; and sun other details of arrangement of parts as'will be readily understood by workers skilled in the art to which the invention relates, I Y

have illustrated in the accompanying drawings forming a part hereof, the preferred embodiments of the present invention.

In the drawings Fig. 1 is a sideelevation showing my actach-ment in position upon'a camera.

F ig. 2 is a top plan of the attachment.

Fig. 3 is a front elevation'oft he attachment.

Fig; 4 is a horizontal section throughthe attachment. v

Fig. 5 is a front View showing. the interior of the attachment with parts shown in section.

Fig. dis a detail ofthe windingreelwith one covering plate removed.

Fig. 7 is an elevation of the attaching reel for the end of the cord.

Fig. 8 is a top plan of the reel shown in open, and parts in section, of a modified form of the invention.

Fig. 10 is a longitudinalvertical section through the construction shown in Fig.9.

" Fig. 11 is a front elevation of a still further modified form of tlie'invention using a pointer.

Fig. 12 illustrates anend View of a further modified formof the invention, and

Fig; 13 shows a front elevation 'of the' construction shown in Fig. 12.

Referring more specifically to the drawingswherein the same reference letters designate like parts in the several views, 1 indicates the bed ofacamera, 2 the back sectionor housing portion, 3 the front section or lens carryingportion', and. 4 the bellows, of

usual construction, connecting the front and back sections. I My attachment is preferably connected to the back sectionor housing and the'cord carried therebyconnectedto the front section; My attachment (ZOI'DPIISFSSL bracket which is adapted to be secured to the side of the back section or housing by means of the screw 6 or other suitable tasteuingmeans and a box-like structure 7 which is removably carried by the bracket 5, said i)0l;ll trurture having on the hack thereci a dove-tailed projection 8 adapted to be engaged by the inclined flanges 9 of the bracket. The box 7 has the hinged cover 10 which is provided at its free edge with a spring catch 11 provided with an indentation 12 which forms a projection adapted to be received in a notch or recess 13 formed in the BflQfG ot' the ho T no cover 10 is provided with the elongated opening 14 which is preferably covered by a transparent plate 15 so that the numerals of an indicator, to be later described, may be clearly read. Adjacent the edges of this elongated opening lat are provided rows of numerals 16 forming a part of the indicator which will operate and may be read in a manner to be later de scribed.

Itotatably mounted within the box 7 is a reel 17 which is provided on the top with a small pinion or cog wheel 18. A cord 19 is secured to the reel, and adapted to be wound thereon, said cord having its inner end secured to the reel by passing its end through the openings 20, formed in the top of the reel. and tying or securing in any other suitable manuer. The cord 19 passes through an opening 21 formed in one end of the box and is provided with a stop 22, in the form oi a head or button, to prevent the cord from being wound upon the reel to such an tent as to draw the free end of the cord with in the box. The reel 17 is provided upon its spindle 23 with a hook member 2% to which is secured one end of a coil spring 25 which has an elongated opening for the reception of the hook. The opposite end of the spring will be secured to the inner periphery of the reel and the spring is so arranged as to nor mally tend to hold the cord 19 wound upon the reel but upon withdrawing the cord from the h using. to unwind from the reel, the

ing will be placed under tension. A pin pcri iery of the reel, and rotatably mountec upon this pin is a sleeve 28 which carries relatively large cog wheel 29 which is secured in the box 7, adjacent the outer i I adapted to overlie the reel 17 and mesh with the small pinion or con wheel 18 carried by the reel. An indicator dial 30 is adapted to be carried by the cog wheel 29 and is preterahly formed on its under surface with projections 31 which are adapted to be received in the openings 32 formed in the said cog wheel 29. By this arrangement the indicator dials will rotate with the cog wheel and they nay be easily removed and new ones replaced when desired. The projections 81 bein;' received in the openings 32 will preventthe indicator dials from rotating independently of the cog wheel 29. The indicator dials will be provided with a series of rows of numerals to cooperate with the numerals along the edges of the opening in the box cover so that the indicator may be read in a manner which will be later apparent. The end of the cord 19 is preferably formed with an eye 33 which will be engaged by a hook 31 carried by a cord secured to the trout section or lens carrying portion of the camera. The cord 35 will be of such a length that when it initially engages the eye the normal diaphragm numbers of the lens at intinity are visible on the indicator dial. The end of the cord 35 opposite to that carrying the book 34: may be secured to the trout section of the camera by ying on in any other desired manner.

In Figs. 7 and 8 I have shown a slightly modified "form of the device for seciu'iug the end of the cord 35 to the front section of the camera. In this arrangement I provide a regulator wheel rotatahly mounted upon a spindle 37, said wheel i-Jti adapted to have the cord 35 wound thereon. A ratchet wheel 38 1s secured to the w 36 and is adapted to be engaged by a pawl 39 which is normally held in eugie'ement with the ratchet wheel by means or the spring l0. The pawl 39 is secured to a plate "1. which carries the spindle 37, and is adapted to be secured to the trout section of the camerain any desired manner. The ord may be withdrawn from the wheat lit; by releasing the pawl 39 from the ratchet wheel 38 so that the hook 3% may be cue with the eye 33 of the cord 19. By this tion the cord may be so adjusted. 3...: to pulling out the frontof the camera. so that the normal diaphragm numbers of ti at infinity are visible on the iudicah In Figs. 9 and 11 I have shown a s h l modified form of indicator carrying; member adapted to be secured to the eanzera. In this form of the invention I provide a box-like structure having the h' d cover 43 which has a spring catch 2-1; of same construction as described for the ferred form of the invention. The 43 is also provided with an elong ted open ing 45 through which the numerals oi the indicator may be read in a manner to be later described. Longitudinaily 5 n d rollers 46 and l? are rotataljdy moan l 5 ill the box 42 and are provided adjacent one end with teeth 4:8 adapted to cup I rations L9 in an endless be t or api'ou 5 0 which operates around the rollers. This end ess belt or apron 50 carries an indicate-r 51 having a plurality of nur adapted to be read through the opening 45. The roller at? has secured to its end, outside of the box 42, a cog wheel 52 which is adapted to mesh with a small cog wheel or pinicn 53 mounted on a spindle secured the ISO lit)

iront faceof the box. This small pinionor cog wheel 53 carries a reel upon which a cord 56 is adapted to be wound. It. will thus be seen that; when the cord is unwound from the reel 55, the pinion or cog wheel 53, meshing with the cog wheel. 52 will rotate the drum 47 and thereby operate the belt or apron 50 and the indicator 51 so as to bring different rows of the numbers of the indicator into position beneath the opening 45. In order that the cog wheel 52 may be disengaged from the pinion or wheel 53 the roller 47 is adapted for sliding movement transversely of the box. In or er to normally bring the wheel 52 into mesh with the wheel 53 a coil spring 57 surrounds the spindle 58 on the end of the roller 57 between the face of the box and the shoulder of the roller. On the back of the box is provided a dove-tailed projection 58 which is adapted to engage the bracket securcdto the side of the rearsection of the camera in the same manner as the preferred form described, so that the box may be detachably connected inposition. It willbe understoodthat the cord 56 will be used in the same manner as the cord 19 described in the preferred construction.

In Figure 10 Ihave illustrated still another modified form of the invention wherein the box or housing, adapted to be detachably secured to the rear section of the camera, is indicated at 59 and is provided in one edge with an opening 60 through which may pass the cord 61 which is adapted to be wound upon a reel, notshown, in the interior of the housing. The reel operates, or rotates, an indicator. dial 62 which is visible through an opening 63 formed in the cover 64 and said indicator 62 cooperates with apointer 65 which is stationary and has the F/ or U. S. (universal system) numbers thereon. As the reel will be constructed in the same manner as that described in the other forms ofthe invention it is thought that a further detaildesoription theneof'or. a

detail showing thereof unnecessary. It will be understood that asthe-oord 61 is unwound from the reel thereel will rotate the dial 62 so as to bring different rows of numerals to cooperate with the numerals upon the stationary hand or pointer 65.

A still further modification is shown in Figs. 12 and 13 in which a ring or flange 66 is formed around an opening 67 in the lid orv cover 68 of the box. In this form of the invention an indicator disc or dial 69 is provided with an opening 70 which will receive the ring or flange 66 and thereby mount the disc or dial upon the box. In

this form the disc or dial mentioned, which may be known as the exterior disc or dial,

may be used either alone or in cpn'nection with a smaller interior indicator disc shown at 71'and a pointer 72. Indicator discs or dials having various numerals thereon. may be calculated for lenses of various focal lengths and these larger indicating discs or dialswill be used for instance in enlarging, copying and reducing. The indicator disc will be placed on the ring or flange 66 so that the figure representing the size of plate to be enlarged is opposite the pointer. The distance is then read oil either on theinside or outside rim of the indicator disc and the camera is extended until this distance is shown opposite the pointer on the small interior disc. The camera is then correctly positioned for the enlargement in question, the distance of the enlargement from the lens also being shown on the indicator disc.

From the above detail description it is thought that the construction and operation of the several forms of the invention will be clearly understood. The indicator dials ordiscs are marked with the diminished light intensity values of the apertures of the lens for every increase of one inch (or other suitable unit or units) in the focal distance up to twice the focal length of the lens in use, or other suitable distances beyond this, if required. The ures may be marked on the indicator clock wise or counter-clockwise, vertically, laterally, radially, circumferentially, spirally or other way. The outer cover of the appa ratus is marked with the normal diaphragn'i numbers of the lens, vertically, laterally, radially, circ-umif'erentia-lly. spirallyor other.

way, according to the uniform system or according to the F/ system or any other system or the slot may be marked with the normal diaphragm numbers according tothe other system on the other'side. The figures on the outer cover are placed so that the diminished light intensity values appearing through the slot may be read off against them, each to the one of which it is the equivalent at the distance to which the camera has been extended. In modified forms of the invention the normal diaphragm numbers of the lens may be arranged upon pointers to operate with rotatable indicator dialsmarked with the diminished light intensity values of the apertures of the lenses. The cord carried by the reel of the indicator box will be unwound from the reel as the front section, or that part carrying the lens, is extended and said'cord may be secured to saidfront seetionin any of the ways described above in the detailed description. The length of the cord when attached to the camera front section, may be so adjusted that when taut &

diminished light intensity values calculated for the apertures of len es of different focal lengths thus permitting the device to he used with diti'erent lenses. The indicator card: may he removed at will and rep aeed by lifting up the hinged cover and these cards may aleo in; ieate the number of times the focal length oi the lens at infinity point is cont 'ned in the various inereaeed i oeal distances: the nuraliie. of times the exposure required for the aperture at normal toeal length has to he multiplied \n'l'ren that an ertuLe is used at the various increased focal distances, the toeal tllfi'till'ltt at each unit xtension oi the cyn ra point: the er terent apertnr 0t tl increased "focal (i ta the exposure requi e;. to size: the number if t'simage of an object on t; or reduced corresptradin the screen is cnlarcienl p to the. extension of the camera, and the conjugat ioci the lens for each den ee or enlargement or reduction, that is I tustanee of object from the lens (or nodi. same) and the distance of the ative from the lens (or not the distance troin lens same) to the object and screen or negative to the point of same) and the di" image which an object o a the average height ol a 1212111. 5 inches) will produce at lengths: and the distance o erg red from the small pinion or cog; wheel 18 bv opening the cover and r Kilt! Said on wheel 29. In that form oi. the invenion where... the two rollers are used. as

previousl stated. the co wheel 52 may be d' "tired from th wheel :13 hr pushthe roller inst the tension of .L described nvv invention what 11 .ew and des re to secure by Letters Patent is:

1. The conihination with an extensible camera. of means operable hr the QFT EQUElOH oi the 'ainera for indicating); the redueed light intensity values oi the apertures oi the lens.

3. The combination with an extensible elated part with the id part with the e);-

camera. 0'! means asso staidrr portion a.

combination with an extensible de achable nieaiis- QSI-O jlilifltl part porizon and part with [or indicatnig the rer values of the apertures rith an exteneihle 'lor shoving the reot the L pertnres i' c t/crating the inol the camera. eaniera includpart,

or ehowing tne redueed .t the apertures of t t one of the parts end with the otaer part for later.

'icn with a camera includ and an QTZiIOHHllDlG part, showing the reduced or the apertures ot' the eonneeted to one of the parts .toeiaied with the other part mhl ('Oi'lilO'fitWl with the indicator e indicator.

iatiou with a camera includt and an e:-;tensible part,

or for showing the reot the apertures ed with one of the parts eoeiated with the other part for indicator.

he eoinb nation wi -4 operable a for lndicatinu the reduced i or one.

light inter. values at the lens. aid means eoinprisino; a stationary part marked with the norina diaphragm nui'nli-ers ot' the lens and a movable part marked with the diminished light intensit values of the E}?"it'lil'(l3 oi the lens.

9. The combination with an extensible era, oi an indieator operable hr the. exn ot the eznnera for indicating the res .CGCl ligrht intensatv values. of the lens. said indieator comprising a stationar part- .nznflz d with the normal diaphragm nun1 here of the lens and a nio ,'ahle part marked with the diminished light intensity values of the apertures oi the lens.

ln testimony whereof I. hereunto alliX my signature.

\VILLIAM GEORGE RICKMAN. 

